How the split works
A fair split starts with one idea: part of the rent pays for space everyone uses, and part pays for the room each person sleeps in. This calculator lets you pick how big each part is, then divides them differently.
- Common areas. You choose what share of the rent covers the kitchen, living room, hallways and shared bath (30% by default). That amount is split equally per person, so a couple in one room pays two shares.
- Private rooms. The rest is split by points. With Room size only, a room’s points are its square feet. With Room size + features, size is blended with an equal baseline (you set how much size matters), then multiplied up for a private bath or a closet and up or down for light on a 1–5 scale.
- Each share = common share + (room points ÷ all points) × private part of the rent.
The other two methods ignore rooms. Equal per person divides the rent by headcount. By income divides it in proportion to each room’s yearly income, which some couples and friends prefer when incomes are far apart.
Worked example
Three roommates rent a $4,200 three-bedroom. The bedrooms are 160, 120 and 95 square feet. They agree 30% of the rent ($1,260) pays for shared space, which is $420 each. The other $2,940 is split by size: the rooms total 375 square feet.
| Room | Sq ft | Common share | Room share | Monthly rent |
|---|---|---|---|---|
| Room A | 160 | $420.00 | $1,254.40 | $1,674.40 |
| Room B | 120 | $420.00 | $940.80 | $1,360.80 |
| Room C | 95 | $420.00 | $744.80 | $1,164.80 |
| Total | 375 | $1,260.00 | $2,940.00 | $4,200.00 |
An equal split would be $1,400 each. Room A pays $274.40 more than that and Room C pays $235.20 less. If Room A also has the only private bathroom, switch to the weighted method and add a bath premium; the calculator recomputes everyone’s share so the total still equals the rent.
Choosing the numbers
No law or agency sets these weights, so treat the defaults as a starting point to negotiate from. A larger common-area share pulls everyone toward an equal split; a smaller one makes room size matter more. Measure rooms the same way (wall to wall, closets excluded or included for all), and agree on the method before anyone picks a room.
The NYC roommate rules that do apply
New York’s Roommate Law, Real Property Law §235-f, controls who may live with you, not how you split costs:
- If you are the only tenant on the lease, you may live with your immediate family, one additional occupant and that occupant’s dependent children. You or your spouse must live there as a primary residence.
- If two or more tenants are on the lease, the total number of tenants and occupants (not counting dependent children) cannot be more than the number of tenants named on the lease.
- You must tell the landlord an occupant’s name within 30 days after they move in, or within 30 days of the landlord asking.
- An occupant who is not on the lease gets no right to stay if you leave unless the landlord agrees in writing.
Your split does not change what the lease says you owe the landlord. If a roommate stops paying, the landlord looks to the tenants on the lease. A roommate renting from you, rather than living with you, may be a sublet with its own rules; see subletting rules in New York and the New York roommate law guide.
Next steps
Check that each share fits each person’s budget with the rent affordability calculator, and split variable bills month to month with the utility bill split calculator.